1. Field of the Invention
This invention concerns the purification of acetonitrile and, more particularly, the removal of oxazole from acetonitrile by contacting the oxazole/acetonitrile mixture with molecular chlorine.
2. Description of the Prior Art
Oxazole has been removed from nitriles by a variety of techniques. U.S. Pat. No. 4,208,329 issued June 17, 1980 discloses a technique for removing oxazole from acrylonitrile by contacting the nitrile with sulfuric acid thereby forming oxazole sulfate and subsequently separating that sulfate from the acrylonitrile. U.S. Pat. No. 3,524,875 issued Aug. 18, 1970 discloses the removal of oxazole from acrylonitrile by distillation while U.S. Pat. No. 3,686,263 issued Aug. 22, 1972 removes oxazole by complexing that compound with certain metal salts.
U.S. Pat. No. 4,308,108 issued Dec. 29, 1981 discloses numerous processes for the purification of acetonitrile including the removal of hydrogen cyanide, allyl alcohol, oxazole and water, e.g., by alkali treatment and extractive distillation. The patentees disclose that oxazole is removed from acetonitrile by subjecting the crude acetonitrile to extractive distillation in the presence of minor amounts of water. This technique is effective but requires large amounts of energy.
Oxazole is recovered from an aqueous acetonitrile solution by complexing the oxazole with an inorganic cadmium salt and subsequently contacting the resultant precipitate with an acid, e.g., hydrochloric acid according to the teachings of U.S. Pat. No. 3,522,268 issued on July 28, 1970. A process for the recovery of unreacted alpha-unsaturated nitriles from a gas phase chlorination by contacting the unreacted nitriles with iron, aluminum or their oxides and thereafter separating the nitrile from the iron or aluminum is disclosed in U.S. Pat. No. 3,801,622 issued on Apr. 2, 1974. U.S. Pat. No. 3,203,975 issued on Aug. 31, 1965 discloses a process for the removal of contaminates from nitrogen containing, water soluble compounds, such as acetonitrile, by contacting the nitrile with calcium chloride, acidifying the resultant mixture, separating the resultant oil layer and further treating the oil layer with additional calcium chloride to finally obtain a purified nitrile.
British Pat. No. 1,500,329 published on Feb. 8, 1978 discloses a process for the removal of allyl alcohol from acetonitrile by contacting the acetonitrile with chlorine. Although the patentees recognize that other impurities may be present which react more rapidly with the chlorine than does allyl alcohol, there is no disclosure or suggestion that oxazole is present or is reacted.
British Pat. No. 1,156,713 published on July 2, 1969 discloses a process for the recovery of oxazole from aqueous solution together with acetonitrile by treating the solution with a suitable inorganic salt such as mercuric chloride, calcium chloride, etc. and thereafter recovering oxazole from the oxazole/inorganic salt complex.